Conventionally, recent telecommunication technologies provide a variety of systems of portable telephones such as cellular phone systems, which are mainly classified into analog cellular systems and digital cellular systems known as ‘PDC’ (Personal Digital Cellular telecommunication system), and ‘PHS’ (Personal Handyphone System). At reception of incoming calls, portable telephones produce incoming call sounds to notify users of reception of incoming calls. As incoming call sounds, portable telephones conventionally produce beep sounds, which may be offensive to ears of users. Hence, recent portable telephones produce melody sounds, which are substituted for beep sounds, as incoming call sounds.
The aforementioned portable telephones may be capable of merely reproducing simple melody lines, which may not be satisfactory in sound quality.
In order to cope with the aforementioned disadvantage, engineers have made propositions that music playback devices having automatic performance functions would be installed in portable telephones. That is, a music playback device, which is applied to a portable telephone to realize an automatic performance function, is constituted by a central processing unit (CPU), a read-only memory (ROM), a random-access memory (RAM), and a sound source, for example. Herein, the CPU runs automatic performance programs stored in the ROM, so that music data representing the melody and rhythm of a prescribed musical tune are read from the ROM or RAM while tone-generation parameters are adequately set to the sound source. Thus, the music playback device reproduces the melody of the musical tune.
Recently, engineers have developed so-called ‘melody ICs’ that are designed to reproduce melodies. An example of the melody IC comprises a sound source, a sequencer, and a ROM for storing musical score data. Upon receipt of reproduction instructions from the external device, the melody IC reproduces a melody of a prescribed musical tune based on musical score data stored in the ROM. When a melody IC is installed in a portable telephone, the CPU is reduced in processing load because it is not required to perform a music playback process. For this reason, the portable telephone can be designed using the low-cost and low-speed CPU for processing thereof.
In the aforementioned music playback device comprising a CPU, a ROM, a RAM, and a sound source, the CPU performs a so-called sequencer process in which music data are translated to adequately set tone-generation parameters to the sound source. For this reason, the CPU is increased in processing load. In addition, the portable telephone using the music playback device cannot be designed using an inexpensive CPU which cannot not bear increasing loads in processing.
The portable telephone using the melody IC is advantageous because the CPU is not increased in processing load. However, it has a problem due to limitation in ‘reproducible’ musical tunes.
To cope with the aforementioned disadvantages, the present applicant has filed two patent applications in Japan, namely Japanese Patent Application No. Hei 11-222319 and Japanese Patent Application No. Hei 11-309408. Those patent applications provide music playback devices that are applicable to portable telephones to allow reproduction of a variety of musical tunes with the low cost.
The portable telephones using the aforementioned music playback devices reproduce musical tunes by hardware elements, e.g., FIFO (First-In-First-Out) memories. That is, music data of a reproduced melody is specified upon issuance of a trigger in response to an incoming call and is then transferred to the FIFO memory. Hence, there occurs a small time delay between the trigger for initiating reproduction of the melody and reproduction timings of actually reproducing melody sound.
It is an object of the invention to provide a portable telephone and a music playback method by which an unwanted time delay is reduced between a trigger for specifying music data whose melody is to be reproduced and reproduction timings of actually reproducing melody sound.